Meagan Koster heard the tree branches break as the bull elk moved closer. He grunted, then stopped broadside in front of the 17-year-old Koster. She pulled the trigger on her crossbow.

The elk moved 15 yards before collapsing.

She knew the elk she shot Sept. 21 was big, but she didn’t know how big. Measuring more than 377 inches, it set the new Safari Club International world record for a North American elk shot with a crossbow.

Antler sizes on the biggest Rocky Mountain elk haven’t changed much during the past century. It’s as easy now — or hard, depending how you look at it — to shoot a record elk like Koster’s as it was in the early 1900s. But, recent research shows, for some species, average sizes of the biggest animals are shrinking.

Average horn and antler sizes of more than 14 trophy categories of mammals in North America have decreased in the past century, according to research in a paper entitled “Effects of harvest, culture, and climate on trends in size of horn-like structures in trophy ungulates” published in February in Wildlife Monographs.

The decrease could be due to hunting pressure on males, according to the paper. It was written by a team of researchers from Idaho State University, wildlife biologists from Arizona and California game and fish departments and the Boone and Crockett Club professor at the University of Montana.

By analyzing the Boone and Crockett Club’s comprehensive record data, the scientists wanted to see if horn and antler size had changed over time, said Kevin Monteith, a researcher at the University of Wyoming, who was finishing his Ph.D. If it had changed, they wanted to know why.

“There is this rigorous, long-term data set that’s been acquired and collected and no one has really looked at it,” Monteith said.

Theodore Roosevelt started the Boone and Crockett Club in 1887 in response to disappearing big game species, such as bison and pronghorn, said Paul Krausman, a co-author and the Boone and Crockett Professor at the University of Montana.

The club formed to help bring large mammals back. Its members were instrumental in forming national parks like Yellowstone and Yosemite.

At the same time, it became a keeper of records.

“That’s where the whack ‘em and stack ‘em part came in,” Krausman said.

Each North American ungulate, or hooved mammal, has a minimum horn or antler size it must meet to be submitted into the record books. The data represent only the largest trophies.

What the researchers found surprised them. From 1950 to 2008, antler sizes of 11 of the 17 trophy animal categories decreased by

1.87 percent. Average horn sizes in three of the eight animal categories decreased by 0.68 percent, he said.

“The reality is they were negative and statistically significant,” Monteith said. “But if you look at it across the board it is less than 2 percent in antler size. That’s very little.”

The researchers looked at all possible variables including climate change and an increase in entries. An increase in hunting of males was the only consistent factor, Monteith said.

As animals such as deer and moose age, their antlers grow. If more males are killed before they reach their peak antler size, average trophy size could decline, Monteith said.

(2) Comments

Unfortunately, this analysis is only capable of looking at the antler measurements and comparing them over time. I have always contended that B&C should have also recorded the age of the animals as that is a huge factor in determining the size of the antlers. As both an Official B&C Scorer and a biologist, I have often reflected that the age of the animal should factor into the overall score. For example a mule deer buck scoring 200 B&C is considered a trophy animal; however, if we factored in the age of the animal as well, a 4 1/2 year old buck would score 900 (200*4.5) versus a 5 1/2 year old scoring 1100 (5.5*200).The average age of harvest needs to be looked at more rigorously by our state wildlife management agencies. Not just for trophy quality or purposes but for the overall health of our wildlife herds. Anyone that has had the opportunity to observe populations with good representation from all age classes of bucks has no doubt noticed a big difference when that population is contrasted with a population comprised mainly of yearling males with few mature males present but scattered throughout their population. Doctor Valerius Geist pointed out some of the problems with the manner in which many western states manage mule deer herds in a book entitled "Mule Deer Country". It was published in the early 1990's (around 1992 I believe). He was rewarded by these same state agencies when they turned on him and began claiming that he was getting "old" & "senile". In my opinion, he had it right all along.As hunting pressure mounts on big game animals, more and more pressure is placed on the males within that population. If no one is collecting the average age of harvest, how can they possibly perceive or catch any shift in the overall average age of animals being harvested if that data isn't even collected?

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